What you need to know about Office 365 Cutover Migration

Migrations are never an easy task and trying to migrate to Microsoft 365 or Office 365 can be hard if the end user is not keen for some downtime or some hiccups along the way. If you have an older version of Exchange like 2010 or Microsoft SBS 2011 then you need to go for the cutover migration. If you have Exchange 2007 then you will need to use IMAP migration, which in itself has some limitations. First things first, one must take precautions and a good backup of the Active Directory along with the Exchange server is to be taken. We start by creating our Microsoft 365 or Office 365 tenant and verifying the domain so that we have a good start.

Before starting the cutover migration configuration, make sure that the server hosting the Exchange server has been updated with the latest updates and services packs. Running the Best Practises Analyser is not a requirement but it will help the process and solving unwanted issues or complications. Analyse the size of each mailbox and make sure they do not exceed the 15GB as to minimize the implications during upload or bandwidth degradation. I would suggest archiving the mailboxes to keep the last year in the mailbox. This will improve the migration process and reducing the chance of corruption or upload issues.

Office 365 Cutover Migration Steps

• From the Exchange admin center in the Microsoft 365 or Office 365 admin portal. Click on ‘Recipient’ and click on ‘Migration’. Click on the ‘More’ button and click on ‘Migration endpoints’.

• Click on the ‘+’ Sign to create the new endpoint and in the first screen tick ‘Outlook Anywhere’, Click Next.

• In the next screen, you will be prompted to enter the ’email address’ of one of the mailboxes to be imported and the domain account name and password of a user who has administrative privileges on the Exchange server.
• To confirm the endpoint you will need to enter the FQDN which is hosting the Exchange server and the RPC Proxy server which in most instances would be the same as the Exchange Server.
• Here is the tricky part, you must make sure that Outlook Anywhere is working successfully and without any issues.

• After the verification, you will have the Microsoft 365 or Office 365 connected to your Exchange Server. Now, on the Migration screen click on the ‘+’ sign and click on ‘Migrate to Exchange Online’.

After going through the rest of the wizard and entering the required details and credentials, the data will start to copy. After some time, you can go to the same screen and check the progress. If all goes well you will get the status of the mailboxes as Synced and the initial synchronisation is completed.

From this moment, you can cut over the DNS records and assign the licenses to your users. From the Active users, you can either assign the licenses one by one if you have mix of E3, Business Essentials or Premium or by using the bulk actions for the users.

• To change the DNS records, you must open the domains from the setup menu on the left sidebar.

You will be required to enter the additional DNS record with your DNS provider, which are given by the portal in the page. If you want, you can either choose to go with your own DNS provider of use the Microsoft 365 or Office 365 DNS facility which mind you, you still need a DNS provider for the first verification process of the domain, afterwards you can disable it and route the Name Servers (NS) to Microsoft 365 or Office 365 directly.

After adding the DNS entries please note that due to the global DNS propagation, the change to be reflected everywhere it can take up to 24 hours. This may cause some delivery issues during the period and some emails can be delayed but unfortunately, it’s part of the migration headaches.

From here onwards, you can say to the users that they can work on their new mailboxes using mobile and web access. For the local users you need to make sure that any DNS entries pointing to the internet domain are updated. After Exchange has been uninstalled from the server you must make sure that any autodiscover entries are removed and a new CNAME records has been created which is pointing the autodiscover.<your internet domain> to autodiscover.outlook.com like below. Also you must be sure that there are no records which are left there from the uninstall which can cause issues with autodiscover service, so make sure that you clean up your Active Directory Schema after the uninstall.

Once complete this can be tested by opening a command prompt and trying to ping the autodiscover.<your domain>. If it does not work or it is not pointing to the right IP, then run ipconfig /flushdns and retry.

Although it will say Request timed out, you must make sure that it resolved correct to something.office.com. Once this is ready you may go ahead to setup your local Outlook to connect via Microsoft 365 or Office 365. Better said than done as if all goes well and your setup is impeccable, you will have a clean migration, but it can get tricky when it comes to those pesky issues that return misleading error message.

As said in my first paragraph you can say that the above will not work on your Exchange 2003 and below. For that, you would need to use the IMAP migration as contacts, calendar items or task will not be migrated and you would have to export and import these through Outlook. You can migrate up to 500,000 items per user mailbox and each email must not be larger than 35MB. Of course, with IMAP migration you would need either to know the password for the users’ mailboxes or reset them, which would create an impact on your users.

On the other hand, when going through migrations the first thing that comes in mind is to have a low impact on your users and a low administration error from the sysadmin side. EDB to PST Converter takes a few minutes after setting up & migrates mailboxes to Microsoft 365 or Office 365 with the minimum effort .With tons of filtering, you can easily migrate mailboxes to Office 365 with certain dates and other criteria. Stellar Converter for EDB is the best and simpler alternative of the hassle that a cutover migration can bring when migrating to Microsoft 365 or Office 365.